l-Proline catalyzed efficient and convenient synthesis of substituted 2H-chromenes by three-component reaction

Synthesis of substituted 2H-chromenes catalyzed by lipase immobilized on magnetic multiwalled carbon nanotubes

Porcine pancreas lipase (PPL) was immobilized on magnetic multiwalled carbon nanotubes successfully for the synthesis of substituted 2H-chromenes. The catalytic activity of immobilized PPL was much higher than that of free PPL. Effects of reaction medium, temperature, and enzyme dosage were also investigated. Under optimum reaction conditions (acetylacetone (1 mmol), salicylaldehyde (1 equivalent), methanol (10 equivalent), and immobilized PPL (protein content: 30 mg; 65 °C; DMF 5 mL; 5 H), the immobilized PPL showed an excellent catalytic performance on the synthesis of substituted 2H-chromenes. Moreover, the immobilized PPL exhibited satisfactory thermostability, operational simplicity, and reusability in this reaction.

A cascade Claisen rearrangement/o-quinone methide formation/electrocyclization approach to 2H-chromenes

A new approach to 8-substituted 2H-chromenes is developed, featuring a novel cascade aromatic Claisen rearrangement/o-quinone methide formation/6π-electrocyclization.

Synthesis and evaluation of new chromene based [1,8]naphthyridines derivatives as potential antimicrobial agents

Novel chromeno[4,3-f][1,8]naphthyridines derivatives were prepared by multicomponent reaction between 2-((sub)amino)quinoline-3-carbaldehyde 1a–f/2a–f, ethyl 2-cyanoacetate 3 and cyclohexane-1,3-dione 4 in ethanol with l-proline as a catalyst.

Reinvestigation of the reaction between 1,3-diketones and 2-hydroxyarylaldehydes: a short, atom-economical entry to tetrahydroxanthenones

A short and facile access to novel functionalized tetrahydroxanthenonesviaa DABCO-promoted tandem Knoevenagel condensation/hemiketalisation process from easily accessible substrates in a high yield.

A simple and efficient one-pot synthesis of 2-alkyl/aryl/pyridyl substituted 2H-chromenes

A simple and efficient protocol is demonstrated to synthesize medicinally significant new 2-pyridyl/aryl/alkyl substituted 2H-chromenes.

Microwave assisted novel and regioselective functionalization of imidazopyridines with chromene acetals and β-nitrostyrenes

A facile synthesis of novel functionalized imidazopyridines has been accomplished through the condensation of imidazopyridines with chromene hemiacetals or β-nitro styrenes with high regioselectivity and excellent yields in the presence of a catalytic amount of PTSA or InCl₃.

Design and application of the recyclable poly(l-proline-co-piperidine) catalyst for the synthesis of mesityl oxide from acetone

A novel bi-component poly(l-proline-co-piperidine) catalyst was developed for the synthesis of mesityl oxide from acetone. The catalyst is more eco-friendly than traditional inorganic bases, avoiding the generation of corrosive solid, and the catalytic mechanism was studied.

“On water” synthesis of highly functionalized 4H-chromenes via carbon–carbon bond formation under microwave irradiation and their antibacterial properties

Microwave assisted synthesis catalyst-free synthesis water as a solvent anti bacterial properties.